Search

US-20260129712-A1 - UE-Initiated SpCell Access

US20260129712A1US 20260129712 A1US20260129712 A1US 20260129712A1US-20260129712-A1

Abstract

A base station operating as a target. SpCell for a user equipment (UE) receives a message from the UE comprising a UE identity and an SpCell access request, transmits a UE context request comprising the UE identity to a currently serving SpCell and receives a UE context reply from the currently serving SpCell.

Inventors

  • Amr Abdelrahman Yousef Abdelrahman MOSTAFA
  • Fangli XU
  • Naveen Kumar R Palle Venkata

Assignees

  • APPLE INC.

Dates

Publication Date
20260507
Application Date
20220929

Claims (20)

  1. 1 . A method performed by a base station operating as a target special cell (SpCell) for a user equipment (UE), comprising: receiving a message from the UE comprising a UE identity and an SpCell access request; transmitting a UE context request comprising the UE identity to a currently serving SpCell; and receiving a UE context reply from the currently serving SpCell.
  2. 2 . The method of claim 1 , wherein the UE context reply comprises a context of the UE.
  3. 3 . The method of claim 2 , further comprising: transmitting, to a currently serving SpCell, a UE SpCell access request comprising the UE identity; and receiving a UE SpCell access confirmation from the currently serving SpCell.
  4. 4 . The method of claim 3 , further comprising: transmitting an SpCell access message to the UE, wherein the SpCell access message is ciphered and integrity protected using a source SpCell security context.
  5. 5 . The method of claim 3 , further comprising: receiving an RRC SpCell access confirmation message from the UE, wherein the RRC SpCell access confirmation message is ciphered and integrity protected using a target SpCell security context.
  6. 6 . The method of claim 3 , wherein the target SpCell does not receive a response to the SpCell access request within a predetermined time, the method further comprising: transmitting a failure message to the currently serving SpCell indicating the UE failed to respond to the SpCell access request.
  7. 7 . The method of claim 3 , wherein the UE SpCell access confirmation comprises an indication that the currently serving SpCell has released a connection with the UE, the method further comprising: transmitting a connection release message to the UE, wherein the connection release message is ciphered and integrity protected using a source SpCell security context.
  8. 8 . The method of claim 3 , wherein the UE SpCell access confirmation comprises an indication that the target SpCell is to perform a connection reconfiguration with synchronization or a mobility operation, the method further comprising: transmitting a connection reconfiguration message to the UE comprising a synchronization indication or a mobility indication, wherein the connection reconfiguration message is ciphered and integrity protected using a source SpCell security context.
  9. 9 . The method of claim 1 , wherein the UE context reply indicates the currently serving SpCell cannot provide a context of the UE, the method further comprising: preparing a radio resource connection (RRC) setup for a new RRC connection; and transmitting an RRC setup message to the UE, wherein the RRC setup message is transmitted via an unsecured channel.
  10. 10 . The method of claim 1 , wherein the UE context request further comprises UE integrity code and wherein the UE context reply indicates the currently serving SpCell cannot provide a context of the UE, the method further comprising: preparing a radio resource connection (RRC) setup for a new RRC connection; and transmitting an RRC setup message to the UE, wherein the RRC setup message is transmitted via an unsecured channel.
  11. 11 . A method performed by a user equipment (UE), comprising: transmitting a first message to a target special cell (SpCell), the first message comprising a UE identity and an SpCell access request; receiving a second message from the target SpCell, wherein the second message is ciphered and integrity protected using a source SpCell security context; deciphering and integrity verifying the second message; and performing an operation indicated in the second message.
  12. 12 . The method of claim 11 , wherein the second message comprises a connection release message.
  13. 13 . The method of claim 11 , wherein the second message comprises a synchronization indication or a mobility indication.
  14. 14 . The method of claim 11 , further comprising: receiving, from a currently serving SpCell, a list comprising candidate SpCells, measurement parameters for each of the candidate SPCells and thresholds for the measurement parameters; and measuring the measurement parameters for each of the candidate SPCells, wherein the target SpCell is selected based on a measured value satisfying at least one of the thresholds for the measurement parameters.
  15. 15 . The method of claim 11 , further comprising: receiving, from a currently serving SpCell, a list comprising candidate SpCells and criteria for selecting each of the candidate SPCells; and determining the target SpCell satisfies at least one of the criteria.
  16. 16 . The method of claim 11 , further comprising: storing a list comprising candidate SpCells and criteria for selecting each of the candidate SPCells; and determining the target SpCell satisfies at least one of the criteria.
  17. 17 . The method of claim 11 , further comprising: determining a connection reestablishment procedure is to be performed; and selecting the target SpCell to perform the connection reestablishment procedure.
  18. 18 . The method of claim 11 , wherein the UE is currently camped on the target SpCell in an inactive state, the method further comprising: determining a connection resume procedure is to be performed.
  19. 19 . A method performed by a user equipment (UE), wherein the UE has an established Access Stratum (AS) context with a target special cell (SpCell), the method comprising: transmitting a message to the target SpCell, the message comprising a UE identity and an SpCell access request; and receiving an SpCell access response indicating the target SpCell is now a serving cell for the UE.
  20. 20 . The method of claim 19 , wherein the message is ciphered and integrity protected using a security context of the target SpCell.

Description

TECHNICAL FIELD The present disclosure generally relates to wireless communication, and in particular, to UE-initiated SpCell access. BACKGROUND It is expected that connection density in future network deployments (e.g., 6G) will be substantially greater than the density of 4G and 5G networks. Use of existing 4G and 5G RRC connected mode mobility (i.e., handover) methods will be difficult to efficiently and reliably manage in future higher density networking environments. Future network deployments are likely to utilize high frequency bands, which tend to utilize smaller cell sizes than existing cells operating for 4G and 5G service. Accordingly, the number of User Equipment (UE) transitions between cells will correspondingly increase as average cell size decreases. Advancements in artificial intelligence (AI) and machine learning (ML) in UEs may improve mobility decision making. For example, a UE has information on its velocity, history of mobility decisions on commonly used routes, and cell quality predictions based on measurements. The Radio Resource Control (RRC) protocols for 4G and 5G have multiple procedures utilized for achieving the same Outcome but by different means. This increases the RRC layer complexity. SUMMARY Some exemplary embodiments are related to a method performed by a base station operating as a target SpCell for a user equipment (UE)/The method includes receiving a message from the UE comprising a UE identity and an SpCell access request, transmitting a UE context request comprising the UE identity to a currently serving SpCell and receiving a UE context reply from the currently serving SpCell. Other exemplary embodiments are related to a method performed by a user equipment (UE). The method includes transmitting a first message to a target SpCell, the first message comprising a UE identity and an SpCell access request, receiving a second message from the target SpCell, wherein the second message is ciphered and integrity protected using a source SpCell security context, deciphering and integrity verifying the second message and performing an operation indicated in the second message. Still further exemplary embodiments are related to a method performed by a user equipment (UE), wherein the UE has an established Access Stratum (AS) context with a target SpCell. The method includes transmitting a message to the target SpCell, the message comprising a UE identity and an SpCell access request and receiving an SpCell access response indicating the target SpCell is now the serving cell for the UE. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an exemplary network arrangement. according to various exemplary embodiments. FIG. 2 shows an exemplary UE according to various exemplary embodiments. FIG. 3 shows an exemplary base station according to various exemplary embodiments. FIG. 4 shows a call flow diagram depicting RRC based UE-initiated SpCell Access according to various exemplary embodiments. FIG. 5 shows a call flow diagram depicting improved UE-initiated SpCell Access when UE context retrieval fails according to various exemplary embodiments. FIG. 6 shows a call flow diagram depicting improved UE-initiated SpCell Access when a source SpCell decides to release the RRC connection according to various exemplary embodiments. FIG. 7 shows a call flow diagram depicting improved UE-initiated SpCell Access during mobility according to various exemplary embodiments. FIG. 8 shows a call flow diagram depicting improved UE-initiated SpCell Access when a message from a UE integrity verification for a target SpCell fails according to various exemplary embodiments. FIG. 9 shows a call flow diagram depicting improved UE-initiated SpCell Access when UE verification by a source SpCell fails according to various exemplary embodiments. FIG. 10 shows a call flow diagram depicting full network control for RRC Connected Mode Handover/PSCell Change according to various exemplary embodiments. FIG. 11 shows a call flow diagram depicting partial network control for RRC Connected Mode Handover/PSCell Change according to various exemplary embodiments. FIG. 12 shows a call flow diagram depicting fully flexible control for RRC Connected Mode Handover/PSCell Change according to various exemplary embodiments. FIG. 13 shows a call flow diagram depicting RRC Connected Mode Handover/PSCell Change according to various exemplary embodiments. FIG. 14 shows a call flow diagram depicting an RRC connection resume without AS-context established between a UE and a target SpCell according to various exemplary embodiments. FIG. 15 depicts a call flow diagram for random access-based VE-Initiated SpCell Access according to various exemplary embodiments. FIG. 16 depicts a call flow diagram for random access based UE-Initiated SpCell Access when a network is highly loaded and cannot serve a UE according to various exemplary embodiments. FIG. 17 depicts a call flow diagram for random access-based UE-Initiated SpCell Access for connect